Patent GB-1201374-A (GB)
Title: Display panel
IPC: H01J29/39
Filed: 1967-08-23
Abstract: 1,201,374. Electroluminescence. R. L. CLINE. 23 Aug., 1967 [29 Sept., 1966], No. 38858/67. Heading C4S. [Also in Division H1] A storage device comprises a plurality of spaced electrodes 11, electroluminescent material 13, and field-effect semi-conductor 14. The panel has a charge retaining surface 15 which may alternatively be an insulator surface adjacent layer 14, if the latter exhibits inadequate charge retention, as when electrons or positive ions rather than negative ions such as' negative oxygen ions are used, for instance. Charge retention may also be increased by a PN junction barrier layer on the outer semiconductor surface. A photoconductive layer may be included or the field effect semi-conductor may itself be photoconductive. Positive or negative images may be attained by selective charge deposition or neutralization of a uniformly charged area by, for instance, scanning or static corona point sources, oscillation of the panel against a corona point source or a C.R. pin tube, a scanned crossed conductor array with corona points at each intersection to which may be applied video signal modulated voltages or voltages controlled to govern the rate of decay of deposited charges or a fixed voltage to all points for instance (Fig. 8, not shown), means as in Specification 889,664, an electron beam in a C.R.T. incorporating the above storage panel with a barrier grid adjacent the target to which video signals may be applied (Fig. 9, not shown), and when layer 14 or an adjacent insulator is photoconductive by a light image or one or more scanning points of light. In the latter instances, if the dark conductivity is too low the panel may be flooded with radiation, corona charged and then exposed to the radiant energy image. One set of electrodes may be of mesh on the charge retention surface side of the panel and resting on the ridges of the field effect semi-conductor formed by a mosaic of recesses formed in same (Fig. 5, not shown). An opaque layer of lampblack for instance may be included to prevent feed-back (e.g. Figs. 2 and 7, not shown) and a thin insulating layer may be provided between the photoconductive and field effect semi-conductive layers (24) and (25) to prevent direct charge injection into the semiconductor. The transparent electrode may be stannic oxide and the substrate glass or polyethylene terephthalate. Xerographic applications are instanced with a glass plate or fibre optics plate as light coupler between the luminous layer and selenium or ZnO coated plate. Field effect semi-conductors inherently capable also of substantial charge retention include ZnO, PbO, and CdO, while ZnS, CdS, ZnO and CdSe for instance may be in combination with an insulator layer. The semi-conductor may be in a non-conductive resin binder, e.g. polyvinyl chloride in the weight ratio 3/1 to 50/1 and when photoconductive, dyes and sensitizers may be included to increase spectral response, specifically ZnO mixed with a styrene butadiene copolymer, chlorinated paraffin, toluene, Bromophenol Blue, Methyl Green and Acridine Orange. The photoconductor may be Se or a Se-As or Se-Te alloy. A 2 mm. thick phosphor layer is instanced and also dispersion in an epoxy resin binder.